This invention relates to an intake system for an internal combustion engine and more particularly to an intake system that provides better performance throughout the entire engine speed and load ranges and which affords a nevertheless relatively compact configuration.
In the copending patent application of the same title, Ser. No. 845,576, filed Mar. 28, 1986, in the names of Manabu Kobayashi, Kazutoshi Suzuki and Takeo Kondo and assigned to the assignee of this application, there is disclosed an intake system for an internal combustion engine which can be tuned to satisfy a wider number of engine speed and load conditions than conventional systems. The system illustrated and described in that application embodies first and second different length intake passages which serve common intake ports of the engine. By employing different lengths, it is possible to tune each passage to serve different engine speed and load ranges. A throttle valve arrangement is provided for automatically controlling which length induction passage serves the engine cylinders at specific running conditions. Although this arrangement has a number of advantages, it requires two separate plenum chambers with separate air inlet devices. Thus, it is necessary to provide two separate air cleaners and silencing inlets for the individual arrangements. With modern motor vehicles wherein the engine compartment is already extremely compact and filled with equipment, it is difficult to provide such separate intake devices.
It is, therefore, a principal object of this invention to provide an improved and simplified intake system for an internal combustion engine. It is another object of this invention to provide an improved induction system for internal combustion engines that can be tuned to suit varying engine requirements and yet which still employs a common air inlet.
It is yet a further object of this invention to provide an improved induction system and engine layout for a motor vehicle.